A method for preventing the attachment and growth of marine organisms is known, comprising preparing a paint using a copolymer, as a vehicle, obtained by polymerizing a triorganotin (meth)acrylate with another (meth)acrylate to form hydrolyzable triorganotin groups in the side chains of the resulting polymer molecule, gradually dissolving the vehicle upon hydrolysis in the seawater to prevent the attachment of marine organisms to the paint surface, and suppressing the multiplication of marine organisms by the physiological activity of the triorganotin group-containing compound generated, as disclosed in, for example, No. JP-B-57-39250 (the term "JP-B" as used herein means an "examined Japanese patent publication"). Although this method is highly effective for ship bottom paints and antifouling agents for fishing nets, the growth of fishes and shellfishes is adversely affected by the contamination of the seawater by triorganotin compounds released from such paints, and this has become an environmental problem.
It has been proposed to prevent the attachment of marine organisms by the action of a hydrolyzable polymer obtained by using a triorganosilyl (meth)acrylate in place of the triorganotin compound, as disclosed in, for example, U.S. Pat. No. 4,593,055. Known triorganosilyl (meth)acrylate polymers which can be used for the above purpose include a homopolymer of trimethylsilyl (meth)acrylate, and copolymers of trimethylsilyl (meth)acrylate and various (meth)acrylic or vinyl compounds such as methyl methacrylate, butyl methacrylate, styrene, 9-vinylphenanthrene, vinylpyridine, and p-dimethylaminostyrene, as disclosed in, for example, D.N. Andreev et al., Izvestya Akademiya Nauk SSSR, Ser, Khim, 1972, Vol.6, pp. 1411-1413; M. Kurihara et at., Journal of Polymer Science, Polymer Chemistry, Vol.11, No.3, pp.587-610 (1973).
These copolymers, however, are disadvantageous in that the polymerization for obtaining the copolymers is difficult to control because of extreme rapidity of the polymerization of trimethylsilyl (meth)acrylate. Furthermore, they have problems that trimethylsilyl groups in the polymers are easily released from the main chains upon hydrolysis, and stability necessary for handling cannot be obtained due to their poor water resistance.
The present inventors previously found that for enhancing the steric hindrance of a silyl group to control hydrolysis, it is effective to use a monovalent hydrocarbon group having 4 or more carbon atoms as at least one of the organic groups linked to the silicon atom, and they proposed this polymer in No. JP-A-62-79514. (The term "JP-A" as used herein means an "unexamined published Japanese patent application".) However, such polymer is not satisfactory in that the rate of hydrolysis of the polymer in seawater changes considerably with the lapse of time. Illustratively stated, the polymer does not undergo sufficient hydrolysis in the initial stage of immersion to prevent attachment of marine organisms to the paint surface, and after that, the polymer begins to dissolve away quickly with the lapse of time, resulting in a tendency that the paint disappears in a relatively short period of time. Thus, a problem still remains to be further improved.